Shoe for friction clutch



p 5, 1956 J. B. PICARD 2,764,271

SHOE FOR FRICTION CLUTCH Original Filed'Dec. 27, 1949 4 Sheets-Sheet 1IA i uana. I 7 v 4 p INVEN'J'OR. $.51 JOHN 5. Fae/33p Sept. 25, 1956 J.B. PICARD SHOE FOR FRICTION CLUT 4 sneaks-sheet 2 Original Filed Dec.37, 1949 I5 is 56 p 1956 J. B. PICARD 2,764,271

SHOE FOR FRICTION CLUTCH Original Filed Dec. 27, 1949 4 Sheets-sheet 5INVENTOR. JOHN B. P/CARD OWN Sept. 25, 1956 J, B. PICARD 2,764,271

SHOE FOR FRICTION CLUTCH Original Filed Dec. 27, 1949 4 Sheets-Sheet 4as 94 as 87 INVENTOR. JOHN B. P/CAFPD 2,764,271 'sH'oE FOR FmcrroNCLUTCH john B. Picard, Los Angeles, cane, assignor to The NationalSupply Company, Pittsburgh, Pa., a corporation of Pennsylvania Originalapplication December 27, 1949, Serial No. 135,050, now Patent No.2,710,087, dated June 1, 1955. and this application April 2, 1953,Serial No.

8 Claims. (Cl. 192-113) This invention relates to friction clutches andis particularly directed to improvements in air operated frictionclutches of the general type shown in the United States patent to C. S.Smith, No. 1,047,713, granted December 17, 1912.

This application is a division of my copending application Serial No.135,050, filed December 27, 1949, now Patent No. 2,710,087 and entitledAir Operated Friction Clutch.

The principal object of this invention is to provide an improved airoperated friction clutch employing a plurality of shoes moved towardengagement with a cylindrical friction surface by means of a cylindricalrubber-like diaphragm operated by air pressure.

Another object is to provide an improved clutch assembly of this type inwhich the shoe and friction lining attached thereto are normallyretracted from operative position by means of a leaf spring actingagainst a torque bar, the shoe and lining, spring, and torque barcomprising a unitary assembly which may be inserted or withdrawn as aunit into operative position.

Another object is to provide an improved form of pressure responsivecylindrical diaphragm for actuating the shoes and lining towardoperative position.

Another object is to provide an improved form of shoe for a clutchassembly of this type, the shoe being of light- I weight constructionand yet with sufficient strength and stiffness to carry the load imposedupon it, and having provision for air circulation through ports invarious parts of the shoe to promote adequate cooling.

A more detailed object is to provide an improved form of connection forsecuring friction lining to the shoe which supports it. Other and moredetailed objects and advantages will appear hereinafter.

In the drawings:

Figure 1 is an end elevation partly broken away and partly in sectionshowing a friction clutch assembly embodying my invention.

Figure 2 is a sectional view partly broken away taken substantially onthe lines 2-2 as shown in Figure 1.

Figure 3 is an enlarged sectional elevation partly broken away takensubstantially on the lines 33 as shown in Figure 1.

Figure 4 is an exploded view showing the construction of one of theshoes, together with the manner of its assembly with respect to thetorque bar, retraction spring and friction lining.

Figure 5 is a developed view in diagrammatic form, partly in section,showing the path of circulation of air for cooling the friction shoesand for dissipating the heat developed by the contact of the frictionlining with the rotary friction surface which it engages.

Figure 6 shows a modified form of shoe employing asbestos insulation onits outer radius.

Figure 7 shows a further modified form of shoe having spaced outerplates with clearance therebetween for cooling.

2,764,271 Patented Sept. 25, 1956 Figure 8 is a view similar to Figure lbut showing a modified form of clutch assembly having internallyexpanding shoes.

Figure 9 is a sectional view taken substantially on the lines 99 asshown in Figure 8.

Figure 10 is a sectional view on an enlarged scale taken substantiallyon the lines 1010 as shown in Figure 8.

Referring to the drawings, the friction clutch assembly generallydesignated 10 is provided for selectively con necting the shaft 11 withthe rotary sprocket 12. Briefly stated, the clutch assembly 10 includesa plurality of ra-- dially movable shoes 13 each having a block offriction: lining 14 secured thereto which is adapted for frictional.engagement with cylindrical surface 15 on the drum 16.. A torque bar 17extends through the interior of each shoe- 13 and the projecting ends ofthe torque bar are received in openings provided on the end flanges 18and 19. Each and 19.

Air pressure admitted into the annular chamber 22 defined between thediaphragm 20 and housing 21 serves to move the diaphragm 20 and shoes 13radially inwardly to efiect a frictional engagement between the lining14 and the friction surface 15 on the drum 16. A circumferentiallyextending leaf spring 23 is provided within each of the shoes 13.

The central portion of this spring bears against the torque bar 17 andthe outer ends engage within the shoe 13 so that the force of the springacts to retract the shoe 13 radially outwardly to separate the lining 14from the friction surface 15.

Proceeding to the description of the various parts in more detail, theflanged hub 24 may be connected to the rotary shaft 11 by means of asuitable key 25, and this hub 24 may support the end flange 19 by meansof the bolted'connections 26. The flange 19 is in turn bolted to thehousing 21 by means of the threaded connecting elements 27, and theflange 18 is bolted to the housing by means of similar elements 28. Thehousing 21 and flanges 19 function as a unit in service and in effectcomprise a body generally designated 29.

The diaphragm 20 may be molded of natural or synthetic rubber orrubber-like material and is held in place at its opposed ends by meansof annular clamping fins 30 which engage radially extending flanges 31on the diaphragm. Inwardly directed lips 32 extend from the flanges 31and are received within tapered recesses 33 provided on the housing 21.The parts just described serve to clamp the outer ends of the rubberdiaphragm securely to the housing 21 so that air pressure cannot leakthrough the clamping means. The cylindrical diaphragm 20 and itsmounting on the body 29 provide a relatively simple yet, highlyeffective air operated means for moving the shoes 13 toward operatingposition. The diaphragm 20 has only a single wall and does not comprisean inflatable tube of the type shown in the said patent to Smith. Thediaphragm is easier to construct and more reliable in operation. It willbe understood that the cylindrical diaphragm 20 defines the inner wallof the annular pressure chamber 22 and that the housing 21 forms theouter wall for said pressure chamber.

Each of the friction shoes 13 includes an arcuate base plate 34 and anarcuate cover plate 35 connected to iii-764 271 spacers 36; The spacers36 are welded or otherwise se;

curely hired to the arcuate plates 34 and 35. Each of the spacers 36comprises a U-shaped strip mounted on edge and provided with apertures37 and cut-out recesses 38 and 39f'o'r passage of air. I prefer toemploy four spacers forea'ch of theshoes 13 with the spacers posi tionedat the corners of the plates-34 and 35 so that both transverse andcircumferential clearance openings are defined between the spacers.Thetorque bar 17 is received in the transverse opening and the paralleledges 40bit the torque bar are contacted by the end members 41-of thespacer bars. A shallow slot 42 may be provided inthe outer surface ofthe torque bar 17 for reception ofthe leaf spring 23; The leaf spring 23extends--with-in the'circumferential-recess defined between the parallelside-portions 43 ofthe spacers 36, andthej outerends of the sprin 23engage under the arcuat'e' cover plate 35. When tlie torque bar 17 andspring 23 are assembled'with'res'pect-to the shoe 13 the parts remain inassembled positionbecause of the cooperative engagement be't'ween thespring'23 and'the slot 42 in the torque bar 17.

Pr'oj'eetirig trunnions'd i on each end of the torque bar 17 arereceived within" cylindrical apertures 45 provided in the end flanges 18"and :19. As best shown in Figure 1 the'projecting truniiions 44 on thetorque bar 17 fitclosely within the apertures 45 so that the torque bar-17 may have tiltihg movement but cannot move radially with respectto theend flanges 18"and 19. The: trunnions 44 are not completely cylindricalbut as shown I clearly in Figure 4 flat areas 46 form-a portion of eachtrunnion, and these flat areas 'are'coplanarwith the upper 'andlow'ersurfaces'of the torquebar.

Means are provided for se'eur ing the friction lining blocks 14 'to'theshoes lfagand as in the drawings this meansinclndes a plurality ofmetallic anehor strips 47' having diverging sides 48L These strips areadapted to be inserted endwise' into matching dovetail'grooves 49"provided in the friction 'lining' block 14. Bolts 50 extend throughspaced'apertujresffl provided in the an; chorstrips- 47, and the head 52of each bolt is received withi'n'the dovetail groove 49 and between thediverging legs 48. Apertures S3 in the arcuate base plate 34 regEister-with the apertures 51 in the anchor strips 47 so that the'bolts50" extend upwardly through the apertures 53 Nuts54' and'wa'shers55 complete the attachment of the friction-lining "block 14 to the"arcuate base jplate of the" "shoe 13; It win bd'ob'sefrve'd t at theends of the.

spacers 36" are open "to' provide clearance so' that a suitable"wr'en'ch"(no't shown) can be inserted toltigh tenthel nuts54on thebolts' 50. The square heads 52 on the bolts are prevented'fro'm'turning'by' reasonof :theirenl gagementwith the-diverging legs 48 oftjhe anehor strips 47. When-the-friction lining blocki14 has beensecured to the shoe 13't'he upper surfa ce 56 of eachanchor strip 47lies below the lower surface ofthe arcuatebaseIplate w 34 so that thefriction lining block 14 is firmly secured.

When the cylindrical diaphragm 20 contracts i'upon introduction of airpressure into theannular chamber 22,

the' shoes 13 move radially inwardly with respect to the torque bars'17. The lining 1'4"on the" shoes engages'thej friction surface-15 onthe drum 1 6." The drum 16 be securedby means of "threaded connections57' to a Spaced bearings '59 maybe provided for rotatably sup" portingthe sprocket 12'on the shaft 11.

In the operation of thede'v ice air ressure isadrriittedj 1 into' theannular pressiire chamber 22 through supply pipe'60"a'nd passageway61formed i'n 'thehousing' 21.

Since the inner diameter ofthe cylindrical rubberldiawardly Thesho s"135re hr ri hewei ht cbnip'osit' construction as desctihed above, andhence the tendency. of the shoes,

13 to move outwardly under centrifugal force is minimized. When thepressure in the chamber 22 builds up sufiiciently the friction contactbetween the lining 14 and drum 16 establishes a driving connectionbetween the shaft 11 and sprocket 12L Thetorgueistransmitted from thebody 29 to the torque bars'17 and then to the ho 3. thr u h t e ns rmmbe s 4 i th c rs The torqueitlien'passes through the anchor strips 47to the" friction lining 14 and thence to..th'e drum 16.

Upon release of the air pressure in chamber 22 the leaf end plate 19 canbe withdrawn. in an axial directionr The shoes 13 and l ining.14 canthen .be withdrawn inan axial direction since .thetorquebars17 andsprings 23 remain assembled with the shoes 13. each shoe 13,togetherwwith its lining 14,.torque bar 17 and spri ng:23, mayjbewithdrawn axially asa unitary. assemblyfmm Operative position after theend plate 19. has first been removed. Since the springs 23 are .each.

confined within their respective shoes 13 they do not ofier any resistance ,to axial movement of. the unitary shoe asseniblies fromoperative position. Similar. unitary assembliesof shoes, torque bars,springsand new. lining may then be placed in operative position byinserting the nn qasfl nto t eg perturesns in the End flange 1s, andthen s u i thetend flange-19. in place. i

Me ns. are proyided to effect, a; circulation of .air. a H h thefriction clutch assemblywto prevent over-. heating of, the rubber -like"diaphragm 20. As shown in. the dr'awings this 'means inc ludes theapertures 62 and. 63 formed in the end flanges; 18 andl9. The means for.

throng promoting circulation of air also includes, the apertures 37and'cut -out recesses @8; 51115139 onthe spacers 36,so.that a flow ofair may .talge pl ace through the interior of each of {the shoes 1 3betwe en the arcuate .eover and base platesfis and 3 4, llhsufipwoftairis indicated bythe arrowsFigurej. 'lfheisprings 23 have beenomitted from:-Fi g ure 5 for-purposes of clarity of illustration. 1 Thernod ed forin f shoe shown in l-?igur e,,6 is similar. in all respectsto theshoes 1 3 describ e d above, with the exception that asbestosinsulation 64.,i8 applied to the PP fied form of shoe shown in Figurelthupper arcuate plate is formed as two spaced members 65 and-66with anairspace 67 egrtending between them The arcuate. plates 65 and 6,6 ar econnected by means of. circumfer,-,. entially extending ribs 68. In thisform of shoe additional coolingisachievedbecause of the passageways 67,and

therefore ny tendency to overheat the rubber diaphragm 20 is avoidedi'lIn Figures" radially 'outwa'r y toward operative position. In otherwords, the friction clutch is of an internallyexpanding, type insteadofexternally contracting as shown in Figures 1 to this m odifiedform ofclutch assembly the cylindrical rubbers phragniSI isanchored atitsopposed endsto a sleeve 82 hitch extendsbetween the end flanges 83 and84." 'Sec1irin'g"i'ne'aris"85, are'provided .for ..co'nlindrical'diaphragm 81, .andi

M y the same as that. de scribed in connection,with' Figures' 1. to 7.,The pressure...

' etweeri'fthe'frnbherl .diaphr'agmgl 2; The construction bf the'shes T87 is similar to that described in connection with the necting the endsof the, these means 85 "are 'substan chanibe ss'isnefih and the metallic's le eve 8 In other words,-

face jot the shoe for further protectionio the rubber diaphragm; 20against overheating. .,In the modi.

8', 9 and lOjI: have shown a friction clutch assembly generallydesignated 80 which is similar in many respects to the friction clutchlfl but difiers there-. rrompri ciphny in that thefriction shoes andliningrnove I shoes 13 except that the friction lining 88 is secured tothe convex face of the shoe instead of the concave face so that thelining may engage the cylindrical friction surface 89 provided withinthe shell 90. The shell 90 is secured for rotation with the sprocket 91while the sleeve 82 is connected for rotation with the hub 92 which iskeyed to the shaft 93. The internal construction of the shoes 87 andtheir engagement with the torque bars 94 is substantially the same asthat described above. Furthermore, each shoe 87, together with itsfriction lining 88, spring 95 and torque bar 94, may be removed andreplaced as a unit upon removal of the end flange 84. Air pressureadmitted to supply pipe 96 passes through passageway 97 formed in thesleeve 82 and into the annular pressure chamber 86. The rubber diaphragm81 is thus caused to expand radially, thereby moving the shoes 87radially outwardly to bring the friction lining 88 into contact with theshell 90. When the air pressure within the air chamber 86 is releasedthe springs 95 retract the shoes 87 from operative position.

Having fully described my invention, it is to be understood that I donot wish to be limited to the details herein set forth, but my inventionis of the full scope of the appended claims.

I claim:

1. In a friction clutch, a shoe member comprising a pair of radiallyspaced arcuate plates, spacers interposed between said arcuate plates,means uniting the spacers and arcuate plates to form an integralstructure, each spacer comprising a U-shaped ported strip each providedwith an axially extending abutment and parallel legs extendingcircumferentially, the spacers being disposed so that the abutments andthe arcuate plates define an axially extending recess therebetween toreceive a drive member, friction lining means for securing said frictionlining to the outer surface of one of said arcuate plates, said meansincluding threaded attachment means extending through said arcuate plateat locations between said parallel legs of the spacers, said threadedattachment means being accessible from the ends of the shoe memberbetween said parallel legs.

2. In a friction clutch, a shoe member comprising a pair of radiallyspaced arcuate plates, spacers interposed between said arcuate plates,means uniting the spacers and arcuate plates to form an integralstructure, each spacer comprising a U-shaped ported strip each providedwith an axially extending abutment and parallel legs extendingcircumferentially, the spacers being disposed so that the abutments andthe arcuate plates define an axially extending recess therebetween toreceive a drive member, friction lining means for securing said frictionlining to the outer surface of one of said arcuate plates, said meansincluding a plurality of bolts operatively connected to the frictionlining and extending through apertures provided in said arcuate plate atlocations between said parallel legs of the spacers, nuts on said boltsbetween said arcuate plates, the nuts being accessible from the ends ofthe shoe member between said parallel legs.

3. A preassembled shoe replacement unit for an airopenated frictionclutch, comprising in combination: a shoe member having a pair of spacedplate portions, one of the plate portions having friction lining securedto its outer surface, the shoe member having an opening extendingtherethrongh between said plate portions, a torque-bar insertablelongitudinally into said opening and projecting at each end axiallybeyond the edges of the plate portions, and resilient means positionedwithin the shoe member between said plate portions and acting later- 6ally against the side of the torque-bar to move it toward the plateportion having the friction lining.

4. A unitary friction shoe assembly for an air operated friction clutch,comprising in combination: a shoe member having a pair of radiallyspaced arcuate portions, the shoe member having an axial openingextending therethrough between said arcuate port-ions, a torque barhaving a central portion of greater width than thickness and providedwith aligned trunnions at its opposed ends, the torque bar having acentral groove in a surface thereof, the torque bar being insertableaxially into said opening with the trunnions projecting at each endaxially beyond the edges of the shoe member, the torque bar beingradially movable into contact with either of said spaced arcuateportions of the shoe member, and a leaf spring extendingcircumferentially within the shoe member between said arcnate portionsand having a portion wholly received within said groove, the leaf springacting against the torque bar to move it radially.

5. For use in a fluid operated friction clutch having a flexiblediaphragm for moving a series of shoe members radially toward acylindrical friction drive surface, the improvement comprising incombination: a preassembled shoe replacement unit including an arcuateshoe member, the shoe member having internal Walls defining an axialopening and an intersecting circumferential opening, a torque barmounted in the axial opening and movable radially therein, the torquebar having a transverse groove, a leaf spring confined within the shoemember and mounted within the circumferential opening, the leaf springacting to move the torque bar radially, a central portion of the leafspring being received within said groove to prevent axial separation ofthe torque bar and shoe member.

6. A preassembled shoe replacement unit for a fluid operated frictionclutch, comprising: an arcuate shoe member having coaxial sectoralcylindrical face and back surfaces, a friction lining removably securedto said face surface, a shoe member having internal walls defining anaxial opening, a torque bar extending through said axial opening andmovable radially therein and projecting therefrom at both ends, a torquebar having a transverse groove therein, said shoe member having acircumferential opening intersecting said axial opening, a leaf springconfined within the shoe member and mounted within the circumferentialopening, a central portion of the leaf spring being received within saidtransverse groove to prevent relative axial movement of the torque barand shoe member, the leaf spring acting to move the torque bar radially.

7. The combination as set forth in claim 6 in which the shoe member hasa layer of insulation mounted on said back surface of the shoe member.

8. The combination as set forth in claim 6 in which the shoe memberincludes three radially spaced arcuate plate elements, the leaf springand torque bar extending between two of said plate elements, and acircumferentially extending passageway within the shoe member adjacentthe other plate element serving as a cooling p-assageway for aircirculation.

References Cited in the file of this patent UNITED STATES PATENTS1,780,200 Linderrnan Nov. 4, 1930 1,848,059 Frehse Mar. 1, 19322,060,773 Pearmain Nov. 10, 1936 2,402,005 Amundsen June 11, 1946

